Studies have indicated that the contamination of both wet and dry household surfaces with potentially pathogenic quantities of bacteria is widespread. Following a study of bacterial flora in 200 homes, Scott et al., in J. Hyq. Camb., Vol. 89, 279 (1982), concluded that improved decontamination procedures are necessary, particularly at sites which are repeatedly wetted, such as the surfaces of sinks, toilets, draining boards, stoves, washing machines, and the like. However, controlled in-use tests employing dilute aqueous detergents at kitchen and bathroom sites achieved no observable reduction in microbial contamination, while application of aqueous hypochlorite and phenolic disinfectant compositions only produced a significant reduction in contamination levels for 3-6 hours. In their evaluation of disinfectants in the domestic environment, Scott et al., J. Hyq. Camb., Vol. 92, 193 (1984), hypothesized that the rapid recontamination was due both to fresh contamination of surfaces, such as toilets, and to the local multiplication of residual colonies at repeatedly wetted sites, such as sinks.
Compositions intended for the controlled release of a disinfectant from a film of a stabilized hydrophilic polymer are disclosed in U.S. Pat. No. 3,966,902. The polymer complex is stabilized as a metal complex by the addition of an inorganic aluminum, zirconium or zinc salt, such as aluminum chlorohydrol, to the polymerization mixture. The stabilization adjuvant is necessary because upon contact with water, films of simple hydrogels become highly swollen and rapidly elute their additives. Furthermore, dry films, both simple and metal-complexed hydrogels, do not adhere well to ceramic and other hard surfaces and can lose their adhesion completely when wetted.
Other antimicrobial agents have been combined with film-forming polymeric materials to accomplish various ends. For example, U.S. Pat. No. 3,325,436 discloses bacteria resistant latexes that incorporate .alpha.,.alpha.'-azobis(chloroformamidine). Similarly, U.S. Pat. No. 2,689,837 discloses polymeric vinyl halides having improved resistance to deterioration caused by fungal and bacterial attack, which incorporate copper 8-quinolinolate into the polymer. Also, U.S. Pat. No. 3,577,516 discloses a spray-on bandage material using acrylate or methacrylate polymers that may contain germicides or fungicides.
Phenols and thiophenols are known antimicrobial agents that have been incorporated into polymeric compounds. U.S. Pat. No. 2,875,097 discloses the incorporation of phenolic compounds into polymers comprising heterocyclic nitrogen compounds. These polymers are used to render fabrics resistant to fungi and insects. U.S. Pat. No. 2,873,263 discloses an antibacterial polymeric resin used for fabricating plastic articles. These resins are formed by polymerizing an unsaturated monomer, such as an aklyl acrylate, in the presence of certain aromatic phenols or thiophenols.
However, the incorporation of various biocides into polymeric base materials, either by physical entrapment or by ionic complexation, has not satisfactorily addressed the problem of providing a polymeric composition capable of forming thin, stable films that exhibit potent, prolonged antimicrobial action. Therefore, a continuing need exists for an antimicrobial composition capable of forming a polymeric film that can release a biodegradable, antimicrobial agent in sufficient concentrations to provide a surface substantially free of microorganisms. A need also exists for an antimicrobial polymeric film capable of providing a surface with prolonged resistance to microbial growth.